FisMat2017 - Submission - View

Abstract's title: An ab initio study of solitary-cation properties in InxGa(1-x)N alloys
Submitting author: Francesco Filippone
Affiliation: CNR - Istituto di Struttura della Materia
Affiliation Address: via Salaria km 29,300 I-00015 Monterotondo (RM)
Country: Italy
Oral presentation/Poster (Author's request): Oral presentation
Other authors and affiliations: Giuseppe Mattioli CNR-Istituto di Struttura della Materia via Salaria km 29,300 I-00015 Monterotondo (RM) Aldo Amore CNR-Istituto di Struttura della Materia via Salaria km 29,300 I-00015 Monterotondo (RM)

In InN, a genuine band gap opening observed after hydrogenation has been  explained by means of the  ``solitary cation'' model, a multi-H  complex in which the central cation, In*,  is fully separated from the structure [1].
Similar effects of H on the host band gap have been observed in In-rich InxGaN1-x alloys.  Paying attention to these materials, we have theoretically  investigated the In*  properties against  three kinds of disorder, structural, compositional and configurational,  all of them possibly
occurring  in  InxGaN1-x alloys.
As a first, major result we have found that  a same,   general solitary-cation model and mechanism  explain the effects of hydrogenation on the electronic properties of both  InN  and In-rich InxGaN1-x alloys.
Even more interestingly, in these alloys, both the energetics of  the In* solitary cations and their effects on the  band gap result to be thoroughly
independent of their atomic neighborhood, in particular, of the number and spatial distribution of  their cation neighbors.
Significantly, this implies that   band-gap opening effects can be safely predicted in whatever hydrogenated  In-rich  nitride alloy containing different 
In  companions (e.g., B, Al, or Ga) as well as  in InN-containing,  unconventional compounds  (e.g., ZnO-InN), thus  offering novel opportunities for material engineering.

We used Density Functional Theory (DFT) in the GGA+U approach,[2-3] as implemented with plane wave basis sets in Quantum-ESPRESSO [4] suite of programs.

[1] Pettinari et al., Adv. Funct. Mater,  25, 5353 (2015)
[2] Anisimov  et al., J. Phys.Condens. Matter, 9, 767 (1997)
[3] Cococcioni et al., Phys. Rev. B, 71, 035105 (2005)
[4] Giannozzi et al.,  J. Phys.Condens.Matter, 21, 395592 (2009)